You need to look at this from the point of view of a Mexican.
The first caption:
Are you joining a cartel?
Obviously not, no one on is right mind will do that, this is the first clue that it is funny, unless you want to work for the Beltran Leiva cartel and then you are out of luck.
The next one is simple, most tourists will not venture to far away from the main turista areas, right? they flew in.
The other tree are very funny in the context, is it on a tourist area on a guided tour? that is safe!
Are you going to get drunk out of your mind? most RV savvy folks do not drink to oblivion, only the kids on spring break!
And the last one
Are you picking fights with the cartels? only an idiot will do that!
I have shown this to friends and family and they all laugh at the message, do not over analyze this it is actually funny in a cainda true sense, so do not go to far from it.
And yes, you are safe in Mexico!
navegator